It has long been a happy alternative for those reluctant to pop pills for depression.

But the herbal extract St John’s wort now has more than just cheerful converts to testify to its mood-lifting powers.

In what is billed as the most thorough study of the plant, scientists have found it is just as effective as Prozac at treating depression.

It also had fewer side effects than many standard drugs used to help those battling despair.

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Researchers compared the effects of the plant hypericum perforatum – popularly known as St John’s Wort – with placebos or a wide range of old and new antidepressants, including those from the new generation of SSRI drugs, such as Prozac and Seroxat.

A d v e r t i s e m e n t

The findings could prompt more GPs to prescribe St John’s wort. In Germany, it is commonly given to children and teenagers.

Experts do not know exactly how the plant lifts depression, although most believe it probably works by keeping the chemical serotonin, which is linked to positive moods, in the brain for longer.

The study’s lead author, Dr Klaus Linde, from the Centre for Complementary Medicine in Munich, pooled data from 29 studies involving 5,489 patients with mild to moderately severe depression.